Since light bulb has the advantage of an easy installation, incandescent bulb is generally used for nighttime and indoor illuminations. However, the incandescent bulb has the disadvantages of high consumption of electric power and short lifespan (with an average lifespan of approximately 1,000 hours), so that many users have started using the power-saving fluorescent bulb a decade ago to comply with the environmental protection and energy saving requirements. The so-called fluorescent bulb refers to a whole illumination device that includes a fluorescent lamp and a stabilizer and provides an average lifespan of approximately 6,000 hours. Besides the incandescent bulb and fluorescent bulb, many lamp manufacturers start producing light emitting diode (LED) bulb as the LED technology advances. Regardless of the incandescent bulb, fluorescent bulb or LED bulb, the interfaces for the lamp heads of these bulbs are the same, and these lamp heads of the same size have an identical shape, so that the three different types of bulbs can be installed interchangeably to lamp holders of different specifications. At present, one of the common specifications of lamp holders is E26 which stands for the diameter of a screw bulb installable onto a contact socket equal to 26 mm. In addition to the E26 specifications, there are specifications for smaller lamp holders such as E12 and E14.
With reference to FIG. 1 for a perspective exploded view of a conventional lamp holder 1, the lamp holder 1 comprises an insulating base 10, a contact plate 11, an anode plate 12, a contact socket 13 and a cathode plate 14, and the insulating base 10 includes a first penetrating hole 100 formed on and penetrated through the insulating base 10, and the contact plate 11 and the anode plate 12 are riveted and fixed onto the insulating base 10 by a rivet 15a, such that the contact plate 11 and the anode plate 12 are attached closely with one another, and the anode plate 12 includes an anode wiring portion 120 bent from the anode plate 12, and a screw hole 121 formed on and penetrated through the anode wiring portion 120 and provided for screwing a screw 122 thereon to clamp and fix an anode power cord (not shown in the figure) onto the anode plate 12, such that the contact plate 11 can be electrically coupled to the anode power cord through the anode plate 12. In addition, the contact socket 13 includes two extended portions 130 extended radially inward from the bottom of the contact socket 13, and the cathode plate 14 is disposed at the top side of the extended portion 130, and the contact socket 13 and the cathode plate 14 are fixed onto the insulating base 10 through the two rivets 15b, 15c. In other words, the rivets 15b, 15c are passed through two through holes 140a, 140b of the cathode plate 14 respectively and the extended portion 130 of the contact socket 13, and then fixed onto the insulating base 10.
The cathode plate 14 includes a cathode wiring portion 140 bent from the cathode plate 14, and a screw hole 141 formed on and penetrated through the cathode wiring portion 140 and provided for screwing a screw 142 thereon to clamp and fix a cathode power cord (not shown in the figure) onto the cathode plate 14, such that the contact socket 13 can be electrically coupled to the cathode power cord through the cathode plate 14, and when the bulb is secured onto the contact socket 13, the bulb is electrically coupled to the cathode power cord through the contact socket 13 and the cathode plate 14. With reference to FIG. 2, the contact plate 11 includes a contact portion 110 bent towards the insulating base 10, such that an upper lateral side of the contact portion 110 can be contacted with an electrode of the bulb. Since a distance is maintained between the contact portion 110 and the insulating base 10, the contact portion 110 can have a slight elasticity to be attached closely onto the electrode of the bulb, and the electrode of the bulb can be electrically coupled to the anode power cord through the contact plate 11 and the anode plate 12.
Although the conventional lamp holder has no electric connection issue, yet its manufacturing process is complicated and redundant materials are wasted. In FIG. 1, the lamp holder 1 uses two components including the contact plate 11 and the anode plate 12 for making the anode, and there are many overlapped areas of the contact plate 11 and the anode plate 12 and the overlapped areas are greater than half of the area of the contact plate 11 (and also greater than half of the area of the anode plate 12). Obviously, there is an unnecessary waste. Furthermore, the portion of the cathode of the lamp holder 1 is overlapped with the contact socket 13 through a crescent portion on the cathode plate 14 in order to fix the cathode plate 14 and the contact socket 13 onto the insulating base 10 at the same time. However, such arrangement also incurs a redundant waste of materials and an additional material cost. It results in a high material cost of the conventional lamp holder 1, and a low profit margin for manufacturers.
In FIGS. 1 and 2, after a manufacturer assembles the contact plate 11 and the anode plate 12 to the insulating base 10 in the production process of the lamp holder 1, it is necessary to bend the contact plate 11 by a machine, so that the contact portion 110 is formed on the contact plate 11, and such arrangement incurs a secondary manufacture, not only complicating the production procedure, but also introducing a risk of damaging the lamp holder 1 during the process of bending the contact plate 11 and failing to maintain a high yield rate.
Therefore, it is an important subject of the present invention to improve the structure of the conventional lap holder to achieve the effects of reducing the material cost, simplifying the manufacturing and assembling procedures, and enhancing the production efficiency and yield rate effectively.